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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
     *{margin: 0;padding: 0;}
     div{
         box-sizing: border-box;
         height: 50px;
         border: 1px solid #333;
         float: left;
     }
     @media(min-width: 1100px){
         div{
             width: 20%; 
         }
     }
     @media(min-width: 750px) and (max-width: 1100px){
         div{
             width: 33.333%;
         }
     }
     @media(max-width: 750px){
         div{
             width: 50%;
         }
     }
    </style>
</head>
<body>
   <div></div>
   <div></div>
   <div></div>
   <div></div>
   <div></div>
</body>
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